Apparatus and methods for measuring vibrations using spectrally-encoded endoscopy

ABSTRACT

An apparatus and method according to an exemplary embodiment of to the present invention can provide imaging information associated with at least one portion of a sample. For example, at least two first different wavelengths of at least one first electromagnetic radiation within a first wavelength range may be provided on the portion of the sample so as to determine at least one first transverse location of the portion. At least two second different wavelengths of at least one second electromagnetic radiation may also be provided within a second wavelength range provided on the portion so as to determine at least one second transverse location of the portion. It is possible to obtain a relative phase between at least one third electromagnetic radiation electromagnetic radiation being returned from the sample and at least one fourth electromagnetic radiation returned from a reference to determine a motion of the portion or of particles within or on the portion, whereas the motion is effectuated by at least one of a sound wave. Further, the imaging information of the portion can be provided based on the first transverse location, the second transverse location and the motion.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is based upon and claims the benefit of priority from U.S. Patent Application Ser. No. 60/912,215, filed Apr. 17, 2007, the entire disclosure of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates generally to apparatus and method for spectrally encoded endoscopy and, more particularly to, e.g., apparatus and methods for measuring vibrations using spectrally-encoded endoscopy techniques.

BACKGROUND INFORMATION

Information associated with vibration measurement and associated mechanical deformation can be important for a variety of medical and non-medical applications. One example is its use for determining the biomechanical characteristics of the bones or ossicles of the middle ear. The middle ear bones can transmit the vibrations of the tympanic membranes to the inner ear, where the mechanical motion is translated into neural response. The ability to measure the vibrations of the ossicles at the sound frequency can be useful for the diagnosis of many types of hearing impairment. Currently, the measurement of the vibrations in the middle ear requires an exposure of the middle ear by surgery. A minimally invasive tool for measuring bone vibration is therefore desired, reducing risk and improving diagnosis accuracy.

Spectrally encoded endoscopy (SEE) is a technique that can use wavelength to encode spatial information on a sample, thus allowing for high quality imaging to be performed through small diameter endoscopic probes. Using interferometery, SEE can use the phase of the reflected light to encode depth, and distance. By using a high speed spectral measurement at rates, e.g., higher than the auditory frequency, SEE can measure small spectral phase differences that are associated with sound vibrations. Without any form of scanning in the distal end of the probe, SEE can measure axial motion along one transverse line.

SUMMARY OF EXEMPLARY EMBODIMENTS

Thus, one of the exemplary embodiments of the present invention is to address at least some of the deficiencies of the prior art.

An apparatus and method according to an exemplary embodiment of to the present invention can provide imaging information associated with at least one portion of a sample for at least one such purpose. For example, at least two first different wavelengths of at least one first electromagnetic radiation within a first wavelength range may be provided on the portion of the sample so as to determine at least one first transverse location of the portion. At least two second different wavelengths of at least one second electromagnetic radiation may also be provided within a second wavelength range provided on the portion so as to determine at least one second transverse location of the portion. It is possible to obtain a relative phase between at least one third electromagnetic radiation electromagnetic radiation being returned from the sample and at least one fourth electromagnetic radiation returned from a reference to determine a motion of the portion or of particles within or on the portion, whereas the motion is effectuated by at least one of a sound wave. Further, the imaging information of the portion can be provided based on the first transverse location, the second transverse location and the motion.

The sound wave can include an ultra-sound wave. The sample may be an anatomical structure, at least one portion of a bone and/or at least one portion of an ear. Further, the sound wave may have a frequency of approximately 0.1 Hz to 10 kHz and/or approximately 100 Hz to 20 kHz. The sound wave can impact the tympanic membrane of the sample. A probe can be provided which is configured to be inserted into an anatomical structure. The anatomical structure may be a middle ear. The imaging information may be associated with a sound wave frequency distribution of the sound wave.

BRIEF DESCRIPTION OF THE DRAWINGS

Further objects, features and advantages of the present invention will become apparent from the following detailed description taken in conjunction with the accompanying figures showing illustrative embodiments of the present invention, in which:

FIG. 1 is a schematic diagram of an exemplary embodiment of an apparatus for measuring motion with SEE according to the present invention; and

FIG. 2 is an exemplary image of the SEE interference phase and amplitude variations observed on a human middle ear bone that is undergoing vibration; and

FIG. 3 is an exemplary image of the frequency map represented by a color look-up table, obtained by processing the exemplary SEE interference phase and amplitude variations detected by the exemplary SEE spectrometer;

FIG. 4 a is an exemplary photograph of stapes generated using exemplary embodiments of the apparatus and method according to the present invention;

FIG. 4 b is an exemplary reflectance image of the stapes provided at similar orientation as the exemplary image shown in FIG. 4 a; and

FIG. 4 c is an exemplary raw data magnified image/crop that corresponds to the pixels in the exemplary reflectance image shown in FIG. 4 b marked by a small rectangle therein.

Throughout the figures, the same reference numerals and characters, unless otherwise stated, are used to denote like features, elements, components or portions of the illustrated embodiments. Moreover, while the subject invention will now be described in detail with reference to the figures, it is done so in connection with the illustrative embodiments. It is intended that changes and modifications can be made to the described embodiments without departing from the true scope and spirit of the subject invention as defined by the appended claims.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

A schematic diagram of an exemplary embodiment of the apparatus according to the present invention for measuring motion with SEE is shown in FIG. 1. This exemplary apparatus can include a broadband or rapidly tunable light source 100, a fiber, or free space, coupler 110, a reference mirror 120, an SEE probe 140 directing spectrally dispersed light onto the sample 140, and a spectrometer 150. The spectrometer can be designed to have resolution that exceeds the spectral resolution of the SEE probe, thus possibly producing a fringe pattern 200 that can be superimposed on the spectrum measured by the spectrometer camera. When the separation between the SEE probe and the sample changes in time the fringe frequency 210 changes, and, more notably, the phase of the fringes likely changes. Those exemplary changes can be recorded by the spectrometer with resolutions, e.g., higher than the optical wavelength.

Using one exemplary embodiment of the invention, the exemplary SEE probe can be inserted through a small incision in the tympanic membrane, such as that performed for commonly practiced insertion of tympanostomy tubes. While inside the middle ear, the exemplary SEE probe can image the middle ear ossicles in three dimension, as well as map the frequency response of the bones 300, which can provide an indication on the function of the ossicles. This capability may faciliatte more accurate diagnosis of hearing disorders and open up the possibility of monitoring the response to treatment in a minimally-invasive manner. SEE can also image the entire middle ear, providing a map of the full vibrational distribution of the ossicles.

To demonstrate the measurement of ossicle vibrations, according to one exemplary embodiment of the present invention, a stapes can be mounted to a motion transducer that may be linearly vibrated at auditory frequencies. Further, e.g., a 350 micron diameter SEE probe can be used to image the footplate of the stapes 400. The line camera can be used to acquire spectra at about 10 kHz line rate. The exemplary SEE probe may be slowly rotated to obtain images at a rate of about 5 Hz. The raw data for each image can be composed of 1500 lines, this likely resulting with approximately 100 spectral interferograms per resolution element. The exemplary reflectance image 410 (e.g., of the stapes) generated using the exemplary embodiment of the apparatus and method according to the present invention is shown in FIG. 4 b, next to the exemplary photograph of the stapes at similar orientation 400 (see FIG. 4 b). An exemplary magnified crop/image of the raw data 420 that can correspond to the pixels in the exemplary reflectance image of FIG. 4 b marked by the small rectangle is shown in FIG. 4 c. The exempla vibrations at approximately 1 kHz are shown in the raw data of FIG. 4 c, which can also contains information on sample reflectance, height, and depth.

This exemplary technique/apparatus according to the exemplary embodiment of the present invention can be used, e.g., to characterize the complex motion of the ossicles inside the middle ear after minor surgical exploration. Amplitude, phase and frequency of the sound waves can be measured at a number of locations, and may provide detailed information on, e.g., the three dimensional motion and the mechanical properties of the middle ear bones. The capability of SEE to image vibrations can be applied to other fields of medical imaging, as well as to industrial applications where space dependant vibration measurement may be important. Spectral encoded imaging techniques as used in accordance with the exemplary embodiments of the present invention can also be useful outside the endoscopic settings due to the characteristic high imaging speed, which can potentially provide real time vibration mapping of a sample with a compact exemplary apparatus.

The foregoing merely illustrates the principles of the invention. Various modifications and alterations to the described embodiments will be apparent to those skilled in the art in view of the teachings herein. Indeed, the arrangements, systems and methods according to the exemplary embodiments of the present invention can be used with and/or implement any OCT system, OFDI system, SD-OCT system or other imaging systems, and for example with those described in International Patent Application PCT/US2004/029148, filed Sep. 8, 2004, U.S. patent application Ser. No. 11/266,779, filed Nov. 2, 2005, and U.S. patent application Ser. No. 10/501,276, filed Jul. 9, 2004, the disclosures of which are incorporated by reference herein in their entireties. It will thus be appreciated that those skilled in the art will be able to devise numerous systems, arrangements and methods which, although not explicitly shown or described herein, embody the principles of the invention and are thus within the spirit and scope of the present invention. In addition, to the extent that the prior art knowledge has not been explicitly incorporated by reference herein above, it is explicitly being incorporated herein in its entirety. All publications referenced herein above are incorporated herein by reference in their entireties. 

1. An apparatus for providing imaging information associated with at least one portion of a sample, comprising: at least one first arrangement configured to provide (i) at least two first different wavelengths of at least one first electromagnetic radiation within a first wavelength range provided on the portion of the sample so as to determine at least one first transverse location of the portion, and (ii) at least two second different wavelengths of at least one second electromagnetic radiation within a second wavelength range provided on the portion so as to determine at least one second transverse location of the portion; at least one second arrangement configured to obtain a relative phase between at least one third electromagnetic radiation electromagnetic radiation being returned from the sample and at least one fourth electromagnetic radiation returned from a reference to determine a motion of the portion or of particles within or on the portion, wherein the motion is effectuated by at least one of a sound wave; and at least one third arrangement configured to provide the imaging information of the portion based on the first transverse location, the second transverse location and the motion.
 2. The apparatus according to claim 1, wherein the sound wave includes an ultra-sound wave.
 3. The apparatus according to claim 1, wherein the sample is an anatomical structure.
 4. The apparatus according to claim 1, wherein the sample is at least one portion of a bone.
 5. The apparatus according to claim 1, wherein the sample is at least one portion of an ear.
 6. The apparatus according to claim 1, wherein the sound wave has a frequency of approximately 0.1 Hz to 10 kHz.
 7. The apparatus according to claim 1, wherein the sound wave has a frequency of approximately 100 Hz to 20 kHz.
 8. The apparatus according to claim 1, wherein the sound wave impacts the tympanic membrane of the sample.
 9. The apparatus according to claim 1, wherein the first and second arrangements are provided in a probe which is configured to be inserted into an anatomical structure.
 10. The apparatus according to claim 1, wherein the anatomical structure is a middle ear.
 11. The apparatus according to claim 1, wherein the imaging information is associated with a sound wave frequency distribution of the sound wave.
 12. A method for providing imaging information associated with at least one portion of a sample, comprising: providing at least two first different wavelengths of at least one first electromagnetic radiation within a first wavelength range provided on the portion of the sample so as to determine at least one first transverse location of the portion; providing at least two second different wavelengths of at least one second electromagnetic radiation within a second wavelength range provided on the portion so as to determine at least one second transverse location of the portion; obtaining a relative phase between at least one third electromagnetic radiation electromagnetic radiation being returned from the sample and at least one fourth electromagnetic radiation returned from a reference to determine a motion of the portion or of particles within or on the portion, wherein the motion is effectuated by at least one of a sound wave; and providing the imaging information of the portion based on the first transverse location, the second transverse location and the motion.
 13. The method according to claim 12, wherein the sound wave includes an ultra-sound wave.
 14. The method according to claim 12, wherein the sample is an anatomical structure.
 15. The method according to claim 12, wherein the sample is at least one portion of a bone.
 16. The method according to claim 12, wherein the sample is at least one portion of an ear.
 17. The method according to claim 12, wherein the sound wave has a frequency of approximately 0.1 Hz to 10 kHz.
 18. The method according to claim 12, wherein the sound wave has a frequency of approximately 100 Hz to 20 kHz.
 19. The method according to claim 12, wherein the sound wave impacts the tympanic membrane of the sample.
 20. The method according to claim 12, wherein the anatomical structure is a middle ear.
 21. The method according to claim 12, wherein the imaging information is associated with a sound wave frequency distribution of the sound wave. 